It is increasingly common to provide windfarms for the generation of electrical power. These windfarms may be located offshore or onshore. The presence of such windfarms, or even a single wind turbine, can pose problems to the operation of nearby Radar systems, which may be provided at civilian or military airports or airbases, which will hereafter be collectively referred to as airfields.
The returns from a wind turbine can be relatively large, compared to the return from a desired target, meaning that is potentially very difficult, if not impossible, to identify a wanted target from amongst the returns from a wind turbine or windfarm.
In the following description, reference will be made to a problems caused by a wind turbine, but the skilled person will appreciate that the problem is exacerbated by the presence of more than a single wind turbine in a typical windfarm scenario.
Prior art attempts to address the problem of wind turbines have involved simply ignoring any returns from the direction in which the wind farm is located. This introduces the problem that any aircraft approaching from that direction are not visible, and this is seldom a desirable solution.
Other attempts to address the problem have involved coating the turbine blades with a Radar-absorbent material. This is not found to be particularly effective either, and is rather expensive.
In practical terms, the problem is normally addressed by prohibiting the erection of wind turbines in the vicinity of ATC Radar systems. However, given the growing desire to generate electricity from more environmentally friendly sources, this places an undesirable limit on the locations where windfarms may be erected. This is particularly so in a densely populated country where there are relatively many airfields, which may have overlapping ATC Radar coverage, and which would otherwise rule out vast areas from windfarm consideration.
There is therefore a desire to mitigate the effects of wind turbines, such that they may be erected in the vicinity of airfields and, hence, ATC Radar systems, without adversely affecting the performance of such ATC Radar systems.